Surgical cauterization snare with ligating suture

ABSTRACT

A surgical instrument assembly for use in snare cauterization operations includes a first tubular sheath member containing a metallic electrical snare cauterization loop. A second tubular sheath member is disposed inside of the first tubular sheath member. A flexible suture member is releasably connected to the cauterization loop, and is provided with a one-way slip knot at its distal end thereby forming a loop of a size corresponding to that of the cauterization loop. The proximal end of the suture member is disposed in the distal end of the second tubular sheath member and is releasably joined to a manually-controlled flexible tensioning device. During use of the instrument, the cauterization loop and connected suture member is expanded from a collapsed configuration and passed over a polyp or other body tissue that is to be removed. The suture member is released from the cauterization loop, the slip knot is tightened around the base of the polyp or body tissue to effect ligation, the cauterization loop is tightened around the free end of the polyp and severed. The stalk of the polyp remains securely ligated by the suture.

This is a divisional of co-pending application Ser. No. 08/496,574 filedon Jun. 29, 1995.

FIELD OF THE INVENTION

The invention relates to endoscopic surgical instruments and methods,and specifically to those for use in procedures employing cauterizationsnares to resect tissue and organs prior to their removal.

BACKGROUND OF THE INVENTION

Flexible snares introduced by endoscopes are widely used in surgicalprocedures requiring the removal of selected body tissue or of an organfrom inside of a body cavity. The snare, typically a loop or nooseformed at the distal end of a flexible metal wire, is moved from thedistal end of the endoscope or laparoscope!* by movement of a handle orplunger attached to its proximal end. The snare can be used inconjunction with cautery in order to cauterize the tissue at the site ofthe resection and thereby reduce or eliminate bleeding.

However, depending on the size, condition and nature of the tissue orthe organ that is to be resected by the snare, complications in the formof excessive bleeding at the site can occur. For example, during afiberoptic colonoscopy, a polyp is visualized by the endoscopist and theloop of the metal cautery snare is placed around the stalk of the polyp.The proximal end of the snare is attached to an electrical power source.The snare is tightened upon the stalk of the polyp, the cautery isapplied and the polyp is transected.

Polyps are pre-malignant lesions which, if left in the colon, becomecancerous. There are about 600,000 polypectomies performed each year inthe United States alone. Of these, approximately 200,000 proceduresinvolve large polyps. Large polyps are those measuring 2 cm or more indiameter. A polyp of this size is carried by a stalk that has an arteryrunning through it. The artery supplies the polyp with blood, and whenthe stalk is transected by the snare, there is a danger that this arterywill bleed. The larger the polyp, the larger is the blood supplyingartery in the stalk and the greater the danger of bleeding.

When such arterial bleeding occurs, the lumen of the colon fills withblood, and it is extremely difficult for the surgeon to see the stalkfrom which the blood is spouting. If the stalk can be visualized, theendoscopist tries to re-snare the transected stalk, tighten the snareupon it and, if successful, must then hold the snare in this positionfor 15 minutes hoping for coagulation to occur and for the bleeding tostop. If the bleeding does not stop, or if the stalk cannot bere-snared, the patient has to have immediate surgery, and the segment ofcolon with the bleeding artery has to be resected.

OBJECTS OF THE INVENTION

An object of the present invention is to provide a safer method for theremoval of portions of internal body organs or other selected tissuegrowths from patients, and especially the removal of large colonicpolyps.

A more specific object of the present invention is to provide animproved method for the performance of snare cauterization proceduresemploying endoscopic and laparoscopic methods and instruments.

Another object of the present invention is to provide a snarecauterization technique wherein the risk of an arterial bleed during acolonoscopic polypectomy is greatly reduced.

Another more particular object of the present invention is to provide asnare cauterization technique wherein potential trauma to the patientand time in surgery are reduced.

A further object of the present invention is to provide a surgicalinstrument assembly for use in ligating selected portions of body organsor tissue prior to a snare cauterization procedure.

Yet another, more particular object of the present invention is toprovide such an instrument assembly which enhances the safety andreliability of snare cauterization procedures for the removal of polypsand other selected body tissues from the internal cavities of patients.

Another particular object of the present invention is to provide such aninstrument assembly that is simple to manufacture and thereforeinexpensive.

A further particular object of the present invention is to provide suchan instrument assembly that is easy to use.

An additional particular object of the present invention is to providesuch a surgical instrument assembly which is disposable. A disposableinstrument assembly requires no lengthy sterilization procedure andreduces the spread of infectious diseases, such as AIDS.

These and other objects will be apparent from the following description.

SUMMARY OF THE INVENTION

A surgical instrument assembly for use in snare cauterization operationscomprises, in accordance with the present invention, a flexiblecauterization snare, an electrical conductor operatively connected tothe cauterization snare for feeding an electrical current thereto, and aflexible suture member formed into a loop or noose that is releasablyconnected to the cauterization loop, both the snare and suture membersbeing disposed in a first tubular sheath. The loop in the suture memberis formed by a one-way slip knot tied at the distal, or free, end of thesuture member. An actuator is operatively connected to the cauterizationloop for alternately expanding and contracting the cauterization loopand the auxiliary suture loop. In addition, the suture member isslidably disposed in a second tubular sheath, which in turn is slidablydisposed in the first tubular sheath. The second tubular sheath servesto facilitate the release of the suture member from the loop, thepositioning of the suture member around the selected body tissue to beligated, and the tightening of the slip knot to effect the ligature.

The actuator may include a finger ring or knob at a proximal end of theinstrument assembly for sliding the cauterization loop and thereleasably connected suture member alternately into and out of thedistal end of a tubular sheath member.

Preferably, the cauterization loop is made of a metallic material, andthe suture member is preferably in the form of a highly flexible, softmulti-filament thread.

Pursuant to another feature of the present invention, the cauterizationloop and the suture member are disposed in parallel planes and arecontiguous or proximate to one another. The cauterization loop and thesuture member can be disposed in essentially the same plane.

According to a specific embodiment of the present invention, the suturemember is releasably connected to the cauterization loop by watersoluble adhesive or water soluble filaments that dissolve after a briefperiod of contact with the bodily fluids of the patient at the surgicalremoval site. The suture member is connected to the metal cauterizationloop at a sufficient number of position to insure that it will not beseparated prematurely. The proximal end of the suture member, like thecauterization loop, is connected directed, or preferably via elongatetensioning means, to an actuator (such as a push-pull ring or knob) atthe proximal end of the instrument assembly. Thus, both thecauterization loop and the suture member are separately controlled bymanipulations at the proximal end of the instrument assembly.

As noted above, the assembly further comprises a second tubular sheathmember, movably disposed in the first tubular sheath adjacent theelectrical conductor, and preferably, elongate tensioning meansextending through the second tubular sheath attached to the proximal endof the suture member for tightening the suture member.

Pursuant to another basic conceptualization for the practice of thepresent invention, a surgical instrument assembly for use in snarecauterization operations comprises a flexible cauterization loop, anelectrical conductor operatively connected to the cauterization loop forfeeding an electrical current thereto, and a suture member releasablyconnected thereto. An actuator is operatively connected to thecauterization loop for alternately expanding and contracting thecauterization loop and the releasably connected suture member. Asdiscussed hereinabove with reference to a preferred embodiment of theinvention, the proximal end of the suture member is disposed in a secondtubular sheath which moves longitudinally inside the first tubularsheath and is operatively connected to a control module at the proximalend thereof. Inside the second sheath and attached to the proximal endof the suture member is an elongate tensioning means, the proximal endof which is operative connected to the control module. The controlmodule comprises actuators in the form of handles, finger and thumbrings and/or knobs operatively connected to the proximal ends of thesecond tubular sheath and the elongate tensioning means for effectinglongitudinal movement of these elements.

A method for removing a selected portion of internal body tissues of apatient comprises, in accordance with the present invention, the stepsof: a method of applying a ligature to a selected portion of internalbody tissue of a patient prior to removal of the adjacent tissueutilizing a cauterization loop, the method comprising the steps of:

(a) providing a conductive cauterization loop to which a flexible suturemember is releasably connected, a slip knot in the distal end of thesuture member forming a loop;

(b) at least partially expanding said cauterization loop and connectedsuture member from a collapsed configuration to an expandedconfiguration;

(c) passing the expanded suture member and connected loop over theselected body tissue to be removed;

(d) partially closing the cauterization loop and attached suture memberaround the selected body tissue to be removed;

(e) releasing said suture member from the cauterization loop;

(f) advancing the slip knot on the suture member to securely tighten thesuture loop around a base region of the internal body tissue therebyform a ligature;

(g) closing said cauterization loop so that said cauterization loopengages said selected internal body tissue adjacent to the ligature;

(h) completing the cauterization procedure to sever and remove theselected internal body tissue.

The present invention provides an improved method for the removal frompatients of selected tissue, such as polyps, and internal body organs,via snare cauterization, which method greatly reduces the risk ofinternal bleeding at the site of the polypectomy or other surgery.

In a method in accordance with the present invention, ligation to reduceor eliminate bleeding at the site of a snare cauterization procedure isprovided. An instrument assembly in accordance with the presentinvention is simple to use. Accordingly, risk of hemorrhage and surgeryare reduced. More specifically, time under anaesthesia with theaccompanying side effects is reduced. Concomitantly, the expense ofhospitalization is decreased.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are perspective schematic views, partially in phantom,illustrating the elements of a snare cautery device of the prior art.

FIG. 1A is a perspective view of one embodiment of a snare cauterizationinstrument assembly of the invention in a closed or ready configuration,prior to insertion in the biopsy channel of an endoscope.

FIG. 1B is a perspective view of the snare cauterization instrumentassembly of FIG. 1A in an extended, open configuration.

FIG. 1C is a schematic longitudinal cross-sectional view of a distal endof the cauterization instrument assembly of FIG. 1A, showing thecauterization loop and suture member in a withdrawn or retracted storageconfiguration prior to use inside the distal end of a tubular member ofthe instrument assembly.

FIG. 2A is a schematic partial cross sectional view of a patient's colonwith a polyp, showing the snare cauterization instrument assembly ofFIG. 1A inserted in the biopsy channel of an endoscope which is itselfinserted into the patient's colon, and further showing the instrumentassembly in an initial stage of a snare cauterization procedure.

FIG. 2B is a schematic partial cross sectional view similar to FIG. 2A,showing the loop and the connected suture member of the snarecauterization instrument assembly of FIG. 1A being passed around thepolyp of FIG. 2A.

FIG. 2C is a schematic partial cross sectional view similar to FIGS.2A-2B, showing the loop of the snare cauterization instrument assemblyof FIG. 1A completely passed around the polyp of FIG. 2A.

FIG. 2D is a schematic partial cross sectional view similar to FIGS.2A-2C, showing the suture member of the snare cauterization instrumentassembly of FIG. 1A being tightened around a base or neck of the polyp.

FIG. 2E is a schematic partial cross sectional view similar to FIGS.2A-2D, showing the completed ligature and the loop of the snarecauterization instrument assembly of FIG. 1A in an electricallyenergized state for burning through the base or neck of the polyp.

FIG. 2F is a schematic partial cross sectional view similar to FIGS.2A-2E, showing the polyp severed from the colon wall and release of theproximal end of the suture member prior to removal of the cauterizationinstrument assembly of FIG. 1A.

FIGS. 3A-3C are schematic longitudinal cross sectional views, showingdifferent specific embodiments of a portion of the snare cauterizationinstrument assembly for releasing the suture member after completing theligature.

FIGS. 4A-4C are a series of perspective schematic views illustrating aportion of the surgical instrument assembly of FIGS. 1A-1C in isolation.

FIGS. 5A-5C are a series of perspective schematic views of anotherembodiment of the surgical instrument assembly illustrating its methodof use.

DETAILED DESCRIPTION

A device for snare cautery constructed with elements known to the priorart is illustrated in FIGS. 1A and 1B, and comprises a hand-held snareactuator module 10, a flexible tubular member 2 connected to a distalend of the control module, and an alternately expandable and closablecauterization loop 26 at the distal tip of the first tubular member 2.

Snare actuator module 10 comprises a body member or frame 28 whichincludes a pair of parallel rails 30a and 30b to which a slider member32 is reciprocatably secured. Frame 28 has a thumb hole 31 at a proximalend, whereas slider member 32 has a pair of finger holes 34a and 34b andis fastened to the proximal end of an electrically conductive wire 36which passes through tubular sheath 2 and is joined to cauterizationloop 26. Wire 36 is sufficiently flexible to bend with tubular member 2during the negotiation thereby of curves or bends in a colon duringsurgery. The snare cauterization device is maintained in the closed orwithdrawn configuration of FIG. 1A as it is inserted into the biopsychannel of an endoscope. When the endoscope is in position and thetissue to be removed has been visualized, the loop is advanced to theposition illustrated in FIG. 1B.

Slider member 32 is also provided with an electrical connector 38 whichis couplable to a source of electrical energy. During a severing step ofa cauterization operation, described in detail hereinafter, electricalenergy is fed to loop 26 via connector 38 and wire 36.

The snare cauterization instrument assembly of the invention, asillustrated in FIGS. 1A and 1B, comprises a hand-held control module 20,a flexible first tubular sheath member 22 that is connected to a distalend of the control module 20. A flexible suture member 24 formed with aone-way slip knot 25 at its distal end is releasably connected tocauterization loop 26. Electrically conductive wire 36 is joined tocauterization loop 26 by junction member 23 proximate the distal end offirst tubular member 22.

As shown in FIGS. 1B and 1C, suture member 24 is releasably joined toloop 26 by a plurality of joining means 50. As will be described ingreater detail below, joining means 50 functions to retain the flexiblesuture member 24 proximate loop 26 for positioning about the tissue tobe ligated, and then permits the suture member 24 to be separated fromloop 26. The joining means 50 can take the form of filaments or fibers,a film or web, an adhesive or like material that can function totemporarily secure the flexible suture material from which member 24 isformed to the flexible wire forming loop 26. The joining means 50, afterrelease of the suture member from loop 26, must not interfere with themovement of slip knot 25 as it is tightened around the tissue to form aligature. As an alternative to forming a plurality of individual pointsof attachment as illustrated in FIG. 1B, where a film or web, oradhesive compound is employed, joining means 50 can be continuous.Joining means 50 can be formed from thermoplastic or heat degradablematerials that will melt and/or degrade at the cauterization temperatureattained by loop 26 upon application of an electrical current.

As will be appreciated by one of ordinary skill in the art from therelationship of the elements illustrated in FIG. 1C, the inside diameterof first tubular sheath 22 must be sufficient to permit the easy passageof second tubular sheath 29 and electrical wire 36. The inside diameterof second sheath 29 must be sufficient to accommodate the longitudinalmovement of suture release means 82, and terminates at its distal end ina tip provided with orifice 80. The diameter of orifice 80 is selectedto permit the free passage of the suture member 24, and small enough sothat the outer edge of the tip will engage slip knot 25 and will preventthe passage of release means 82 from sheath 29.

Suture actuator module 60 is also joined to the distal end of controlmodule 20, and includes Y-fitting 62 with branch member 64 thatcommunicate with the axial passage in first sheath 22 through which wire36 passes. Extending from branch member 64 is the proximal end ofelongate tensioning means 27 joined to finger ring 66. Also extendingfrom the opening in member 64 is the proximal end of second tubularsheath 29, which terminates in finger ring 70. As will be discussed inmore detail below, finger ring 70 can be removably engaged with slider32 in order to coordinate the advancement of second tubular sheath 29and conductor wire 36 to facilitate the alignment and positioning ofcauterization loop 26 and suture member 24.

Prior to the beginning of a snare cauterization operation, loop 26 isdisposed in a contracted state together with releasably connected suturemember 24 in the distal end of tubular member 22, as illustrated in FIG.1C. Concomitantly, slider member 32 is retracted to the proximal end ofrails 30a and 30b (towards the right side of frame 28 in FIG. 1A).Tubular member 22 is inserted in a biopsy channel 40 of an endoscope 42,as shown in FIG. 2A, and the endoscope is inserted into a body cavity ofa patient, such as a colon C.

As illustrated further in FIG. 2A, endoscope 42 is conventionallyprovided at its distal end with a pair of apertures 44 and 46 for,respectively, delivering light to, and receiving light from a surgicalsite.

Upon the observation of a polyp P within colon C via the use ofendoscope 42, the snare cauterization instrument assembly is shifted ina distal direction so that tubular member 22 protrudes from the distalend of biopsy channel 40. Then, slider member 32 is shifted in a distaldirection to eject loop 26 and releasably connected suture member 24from tubular member 22. Upon ejection, loop 26 and connected suturemember 24 expand from a contracted or closed configuration into an atleast partially opened configuration, as shown in FIG. 2A.

FIG. 2B depicts a later stage in the cauterization procedure. The snarecauterization instrument assembly of FIG. 1A is manipulated to pass loop26 and suture member 24 around polyp P.

As shown in FIG. 2C, the loop 24 and suture member 24 are lowered overthe polyp P, at which position bodily fluid will come into contact withthe water soluble filaments 50 that join the loop and suture member,dissolving them. In order to assist in separating suture member 24 fromloop 26 and to position suture member for the ligation, second tubularsheath 29 is advanced from the distal end of first sheath 22, as shownin FIG. 2D. Cauterization loop 26 is also partially closed around thetissue of polyp P.

Following its release and separation from loop 26, suture member 24encircles a base region or neck N of polyp P and the polyp is surroundedby suture member 26, as shown in FIG. 2E.

Once the suture member is in the desired position at the base section ofthe polyp P, the distal end of second sheath 29 is further advancedagainst slip knot 25 by movement of finger ring 70 while simultaneouslywithdrawing tensioning means 27 by finger ring 66. After the suturemember has been tightened about the base or stalk of polyp P and theligation thereby completed, the cauterization loop is tightened againstthe adjacent section of the polyp base towards its free end above thesuture and current is applied in order to sever the polyp, as shown inFIG. 2F.

As one step in the procedure, the proximal end of the suture member isreleased from the distal end of the elongated tensioning means 27. Therelease of the proximal end of suture member 24 from the surgicalinstrument assembly is effected in conjunction with suture release means82. As shown in more detail in FIGS. 3A-C, suture release means 82comprises a temporary joining of the proximal end 24P of suture member24 with the distal end of the elongate tensioning means 27 so thatproximal end 24P can be removed from the instrument assembly after theligature is formed. FIG. 3A illustrates an embodiment where the ends ofsuture member 24P and tensioning means 27 are overlapped and tightlywrapped with a band or web 44 of flexible material, such as a polymericmaterial. One end of web 44 can be bonded to elongated tensioning means27 and when the suture member is to be separated, tensioning means 27 isrotated to loosen the web 84; thereafter the tensioning means 27 ismoved proximally and the free end 24P of suture member 24 passes throughorifice 80 in sheath 29.

As schematically illustrated in the embodiment of FIG. 3B, the ends ofthe suture member 24P and tensioning means 27 are twisted around eachother to temporarily join them. In order to insure a sufficiently strongconnection during the tightening of the ligature, a water solublebonding agent can be applied as part of the suture release means 82.After securing the ligature, second tubular sheath 29 is movedproximally and release means 42 passes through orifice 80 and intocontact with body fluids at the site to solubilize the bonding agent andrelease the free end 24P of the suture member.

FIG. 3C illustrates yet another embodiment where suture release means 82comprises an elastomeric sleeve through which pass the proximal end ofsuture member 24 and the distal end of elongate tensioning means 27 inan overlapping configuration. The inward radial pressure exerted byelastomeric band 86 is sufficient to maintain the overlapping relationduring the tightening of the ligature; after the ligature is formed,additional tension is applied by moving tensioning means 27 proximallyto release the proximal end of suture member 24 from band 86. Thediameter of the band 86 is larger than orifice 80 to insure that theband is not left at the surgical site, but is retained in second tubularsheath 29. As will be apparent to one skilled in the art, modificationsto the structures and methods described above can be undertaken in theconstruction of alternate suture release means.

Where the two ends are releasable under the application of a tensioningforce, the finger ring 66 is withdrawn further while the tip of thesecond sheath 29 is maintained in position against the tightened skipknow 25, as shown, for example, in FIG. 2E. Once sufficient tensioningforce has been applied to part the distal end of tensioning means 27from the suture member at 27P, the second tubular sheath 29 is withdrawnfrom first tubular sheath 22, and from the instrument assembly.

Where the two ends are joined by a spirally wrapped filament or web, asillustrated in FIG. 3A, the finger ring 66 is turned in a directionopposite to the spiral wrap until the proximal end of the suture 24P canbe pulled free. Where the two ends are joined by water soluble bindermeans, the joined section is placed in contact with the bodily fluidsproximate the surgical site to dissolve the binder and the ends arefreed by the application of tension to the tensioning means 27.

At that juncture, slider member 32 is pulled back in the proximaldirection, whereby wire 36 pulls loop 24 further back into the distalend of tubular member 22, thereby causing loop 24 to tighten about neckN of polyp P, as illustrated in FIG. 2F.

As also indicated in FIG. 2F, electrical current is then caused to passthrough wire 36 and loop 24. Generally, electric current from loop 24 isconducted through neck N of polyp P, thereby generating in the polyptissues heat sufficiently great to sever and cauterize neck N. Upon thesevering of polyp P at neck N, slider member 32 is pulled farther in theproximal direction, thereby pulling loop 24 further into the distal endof tubular member 22 to essentially close the loop. In a final step, theentire snare cauterization instrument assembly including, in particular,tubular member 22, is shifted in the proximal direction relative toendoscope 42.

In order to further illustrate the method and apparatus of theinvention, reference is made to FIGS. 4A-C where there is shown inisolation the suture member 24, second tubular sheath 29 and actuatormodule 60 and related elements. As shown in FIG. 4A, following itsseparation from cauterization loop 26 by the release of joining means50, the loop of suture member 24 is placed over the polyp and positionedtowards the base of the stalk. Finger ring 70 attached to sheath 29 isadvanced distally until the tip surrounding orifice 80 of sheath 29contacts the slip knot 25. Tension is maintained on elongate tensioningmeans 27 via finger ring 66 and finger ring 70 is further advanceddistally to tighten slip knot 25 around the stalk of polyp P to form theligature, as is shown in FIG. 4B. While the tip surrounding orifice 80is maintained in contact with slip knot 25, proximal end 24P of suturemember 24 is separated from suture release means 82, for example, asshown in connection with FIGS. 3A-3C above. Thereafter, as shown in FIG.4C, sheath 29 containing release means 82 and tensioning means 27 arewithdrawn from the surgical site prior to the cauterization step.

In the further preferred embodiments illustrated in FIGS. 5A-5E, secondtubular sheath 29 passes through orifice 37 in control module 20co-axially with electrically conductive wire 37. As can be seen in FIGS.5A and 5B, finger rings 70 and 66 which comprise actuator module 60 aretemporarily joined to the slider member 32 so that openings 70a and 34aand openings 70b and 34b are aligned when the cauterization loop 26 andsuture member 24 are in the starting or retracted position in the firstsheath 22. The actuator module and slider member are releasably joinedby mating means 39, such as snap or press fit projections andcorresponding recesses on the respective parts, rotationallyinterlocking surfaces (not shown), hook and loop fasteners (sold underthe trademark VELCRO®) secured to the surface to be joined (not shown),and the like. It will be appreciated that mating means 39 are desirableto position the parts in aligned relation so that the surgeon's fingerscan be passed through the openings in finger rings 70 and 34 tosimultaneously advance the wire 36 and tensioning means 27.

As will be understood by reference to the sequence illustrated by FIGS.2A-2F, and the corresponding description, movement of the slider member32 in the distal direction, i.e., from FIG. 5A to FIG. 5B, advances loop26 from the interior of first sheath 22, thereby permitting it to openwith releasably attached suture member 24. As illustrated in FIG. 5C,actuator module 60 is then separated from slider member 32. Finger ring66 is held in position with a tensioning force, and simultaneouslyassembly 70 is distally advanced to move the tip of second sheath 29into contact with slip knot 25. FIG. 5D illustrates the relativeposition of the above elements when the ligature has been formed by thefully tightened suture member 24. Following release of the proximal end24D of the suture member, the second tubular sheath 29 and relatedactuator module 60 are fully withdrawn from the first tubular sheaththrough orifice 80 in the distal end of control module 20.

In a like manner, suture actuator module 60 can be temporarily matedwith slider member 32 in the embodiments illustrated in FIGS. 1 and 2 byappropriate orientation of branch 64 of Y-fitting 62 (not shown). Thesecond tubular sheath 29 should be of sufficient flexibility andresiliency to provide a smooth channel for tensioning means 27.

Although not specifically shown in FIGS. 5A-5E, it will be understoodthat the necessary cautery connections are made to electricallyconductive wire 36 either prior to, or following completion of theligature. In the practice of this invention, the cauterization step isperformed after the ligature is completed.

Every polyp ligated and severed by a snare cauterization instrument asdescribed and illustrated herein should produce little, if any,bleeding. Thus, the time for the procedure will be reduced to a minimum.Trauma to the patient from potential complications due to excessivebleeding is likewise reduced, as are hospitalization expenses.

A cauterization instrument assembly as described herein is of relativelysimple construction, is inexpensive to produce and is preferablydisposable.

Although the invention has been described in terms of particularembodiments and applications, one of ordinary skill in the art, in lightof this teaching, can generate additional embodiments and modificationswithout departing from the spirit of, or exceeding the scope of theclaimed invention. Accordingly, it is to be understood that the drawingsand descriptions herein are proffered by way of example to facilitatecomprehension of the invention and should not be construed to limit thescope thereof.

We claim:
 1. A method of applying a ligature to a selected portion ofinternal body tissue of a patient prior to removal of the adjacenttissue utilizing a cauterization loop, the method comprising the stepsof:providing a conductive cauterization loop to which a flexible suturemember is releasably connected, the suture member formed into a loop bya slip knot at its distal end; at least partially expanding saidcauterization loop and connected suture member from a collapsedconfiguration to an expanded configuration; passing the expanded suturemember and connected loop over the selected body tissue to be removed;releasing said suture member from the cauterization loop; advancing theslip knot on the suture member to securely tighten the suture looparound a base region of the internal body tissue and thereby forming aligature; partially closing said cauterization loop so that saidcauterization loop engages said selected internal body tissue adjacentto the ligature; completing the cauterization procedure to sever andremove the selected internal body tissue.
 2. The method of claim 1 wherethe slip knot is advanced by contacting the slip knot with a distal endof a tubular sheath through which a proximal end of the suture memberpasses.
 3. The method of claim 1 which includes the further step ofapplying tension to the proximal end of the suture member while the slipknot is advanced.
 4. The method of claim 3 where tension is applied tothe suture member by elongate tensioning means joined to the proximalend of the suture member.
 5. The method of claim 4 which includes thestep of releasing the proximal end of the suture member from theelongate tensioning means after the ligature is formed.
 6. The method ofclaim 5 where the proximal end of the suture is released by axiallyrotating the elongate tensioning means.
 7. The method of claim 5 wherethe proximal end of the suture is released by applying additionaltension to the elongate tensioning means.
 8. The method of claim 5 wherethe tubular sheath is withdrawn from the vicinity of the ligature andthe cauterization loop.
 9. The method of claim 1 where the cauterizationloop and releasably connected suture member are inserted through aninstrument channel of an endoscope.